Having clean teeth and healthy gums is an important aspect of daily hygiene. It helps prevent the unwanted expense of dental surgery, tooth loss and the expense associated with repairing or replacing teeth. Improvements in toothbrush design have been made to more effectively clean tooth and gum areas such as the open interproximal area that are likely to develop tooth decay or gum disease. The formation and accumulation of plaque on the teeth is a common cause of gum disease and tooth loss. After plaque is formed, it can be calcified if not removed within a day. Once calcified, the plaque must be removed by a dentist. Almost any tooth brush can be effectively used to remove plaque from the outside or facial surfaces of the teeth. However, removal of the plaque from the inside interproximal surface of the molars, premolars, canine and incisors is inhibited by the angle of the bristles in relation to the handle of the toothbrush. Specifically, the handles of the brushes do not allow maximum contact between the bristles and the inside interproximal surfaces of the teeth. This lack of contact is shown most effectively in FIG. 7 of U.S. Pat. No. 5,046,212. Also, the handles of prior art toothbrushes tend to impair a persons ability to see the surfaces of the posterior teeth they are trying to clean. It important for the person cleaning their teeth to see the areas being cleaned so that areas will not be missed.
One of the hardest places to clean is the inside or lingual surface of the posterior teeth. Previous patents such as U.S. Pat. No. 4,800,608 address the cleaning of the outside of the posterior teeth using a bristle head with an included angle as shown in FIG. 4 of that Patent. U.S. Pat. No. 5,046,212 shows a toothbrush body having a bristle head at one end and an offset neck connecting the bristle head to a straight handle. As shown in FIG. 7, only a portion of the bristles come in contact with the internal embrasure and lingual surface of the posterior teeth. U.S. Pat. No. 4,672,706 shows a toothbrush similar to prior art FIG. 1A of the present application. The bristle head in FIG. 2 of the '706 patent is offset from the longitudinal axis of the handle in a manner that will hinder full contact of the bristles with the lingual surface of the posterior teeth. U.S. Pat. No. 4,356,585 shows a toothbrush head that is located entirely below the longitudinal axis of the handle. The head is not parallel to the longitudinal axis of the handle and the bristle tufts are of unequal length such that the bristles are progressively longer traveling away from the handle. When this toothbrush is placed so the bristles are flat against the lingual or buccal surfaces of the posterior teeth, the offset connecting portion between the head and the handle blocks the view of these surfaces by the person who is brushing their teeth. This is a disadvantage in that some hard to clean areas such as the lingual surfaces of the posterior teeth may be missed or cleaned less effectively. U.S. Pat. No. 4,724,570 shows a toothbrush having a head with bristles that are longer and softer along the centerline and shorter and stiffer toward the outer edge of the toothbrush head to facilitate cleaning of the sulcus and the gingival third of the lingual surface of the anterior teeth. This patent does not address the problem of keeping the handle of the toothbrush away from the anterior teeth so that the bristles can completely contact the inside interproximal surfaces of the posterior teeth. It also does not address the problem of being able to see the inside interproximal surfaces of the posterior teeth when they are being brushed. Other U.S. Design patents such as U.S. Pat. Nos. Des. 336,369, 284,236, 359,167 and 268,795 show toothbrushes that do not address the concerns stated above. To overcome the limitations of those toothbrushes the present invention has been developed.